strange window problem - help!!

[swanny]

hi all,
I,ve only had my boxster for a few months so am still getting used to it-everything so far has been great apart from the "sun visor" problem that try as I may to resolve the situation it looks like it will be "a new one" - however today I lowered the windows but on putting them back "up" again they would only go up three quarters of the way (approx. to the same level that they do when they lower themselves on roof activation) I then took the roof down & the windows worked perfectly - up fully & down fully no problem - I tried again with the roof closed & same problem - has anyone come across this problem before & have a remedy please - thankyou for reading - hope someone can shed some light on the problem,i,m baffled !!